Lateritic Ore Reduction Using Ammonia Gas as an Alternative to Reduce CO₂ Emission in Ferronickel Production

The ferronickel industry requires energy for processing and emits large amounts of CO₂. The enormous energy requirement in the ferronickel industry is due to the low nickel content and high impurities in laterite nickel ore. Furthermore, the ferronickel industry’s high CO₂ emissions can be attributed to the need for reducing agents, such as coal, to reduce nickel and iron oxides. This research aims to study the reduction process of lateritic nickel ore, specifically when NH₃ gas is used as the reduction agent. Several process variables were studied, such as the effects of temperature and time. In addition, thermodynamic analysis was also carried out to determine the possibility of reactions that occurred during the reduction process. Many types of tests were also conducted, including X-ray diffractometer (XRD), inductively coupled plasma (ICP), and scanning electron microscope-energy dispersive X-ray (SEM–EDX) observations. Finally, the higher the temperature and the longer the time used, the higher the reduction degree obtained. It was also possible to obtain the ferronickel phase after the reduction process, which was predicted by thermodynamic calculations and confirmed by XRD. Other impurity minerals such as Fe₃O₄, SiO₂, (Fe, Mg)₂SiO₄, and MgSiO₃ were also found in the reduced product. The best reduction degree in this study was 77.8% when using a temperature of 900 °C and a duration of 120 min. Considering the successful reduction of nickel laterite ore using NH₃ gas, it is theoretically estimated that CO₂ can be reduced by about 22%.